1. Field of the Invention
The present invention relates to a charging apparatus for charging a battery for a vehicle.
2. Description of Background Art
In a three-phase brushless motor, energization control of a stator coil is executed based on an output signal of a rotor sensor arranged corresponding to each phase. However, when output timing of a sensor signal shifts due to an error of an attaching position of the rotor sensor, appropriate energization timing of the stator coil is not secured. Thus, an accurate motor output control cannot be executed.
In JP-A No. 2012-060705, a phase shift between the zero-cross point of an induced voltage of each phase and the rising of a sensor signal is detected as an error of an attaching position of a rotor sensor in a regenerative power generation state of a motor. Also, JP-A No. 2012-060705 discloses a technology for highly precisely controlling energization timing of each stator coil based on the detected phase shift.
Also, in a battery charging apparatus that uses a three-phase AC generator, energization control of each phase is executed based on the sensor signal that detects rotation of a rotor of a generator. Therefore, similarly to the case of the three-phase brushless motor, it is desirable to detect the error of the attaching position of the sensor.
However, in the battery charging apparatus, an output terminal of the generator is connected to a battery and a load through a regulator. Therefore, the method disclosed in JP-A No. 2012-060705 can be applied only in a region of an ultra-low revolution speed (<idling revolution speed) at the time of an engine start when a regulator output current does not flow. Also, there is a problem wherein in a region of less than the idling revolution speed, fluctuation of rotation of an engine is large and an accurate measurement cannot be executed. Thus, measurement can be executed only at a limited timing of immediately after the engine start.